I can't upload the sketchup file or whatever. Every time the program writes that the file is not found. It seems that the program does not have access to the disk.
Save the file does not work either, it just gives an error.
Can you please submit a bug report here and share a copy of your log files (Where to find Twinmotion .log file.) for the support team to investigate? The log files may help us determine what is causing the problem.
Please try to replicate the issue, then close out Twinmotion to generate a log file that will have information relevant to the issue.